1. Field of the Invention
This invention relates to a device for winding webs of material onto winding shafts, comprising a movable bearing supporting a winding shaft during winding, through which the supply roll being formed can be moved towards a contact roller and which can be moved in a position away therefrom for the removal of the completely wound supply roll, and a means for inserting into the movable bearing a new winding shaft which has been accelerated to approximately the speed of the web and onto which the leading end of the web, formed by a severance cut, is wound.
2. Description of the Prior Art
A combined contact and central winder is known from German Patent Publication DE-PS 32 12 960. The winder has a pair of receiving arms, pivotable about the axis of the contact roller, which receive a new winding shaft in a vertical position which, after its acceleration to the speed of the web, is lowered by a pair of frictional wheels onto a contact roller rotating at the same circumferential speed for winding the leading end of the web, severed by a severance cut, thereonto.
Then the receiving arms are pivoted by about 90 degrees so that the journals of the winding shaft can be inserted into the receptacles of a slide which moves away from the contact roller in accordance with the increasing diameter of the supply roll being formed. After effecting the severance cut, the slide is moved away from the contact roller to such an extent that the completed supply roll can be removed. Then the slide moves back in the direction towards the contact roller so that the receiving arms can insert the bearing journals of the winding shaft into the receptacles of the slide. In the known winding device, the winding shaft together with the supply roll being formed thereon are supported on the contact roller until the completely wound supply roll has been removed from the slide and the slide has again been moved back into its receiving position adjacent the contact roller. During this period of time, due to the high winding speed, a supply roll with such a large weight is formed that, because of the contact pressure, the web of material may be damaged. In particular when the web to be coiled is a thin film, damage to the film can be caused by the weight of the supply roll being formed so that the webs will become rejects. Furthermore, disturbances can occur in the web tension when it is switched from the frictional wheel drive being active until the newly coiled winding shaft is situated in the receptacles of the slide, to the central drive of the winding shaft (switching over of the drives when there are large winding diameters).